Solved Installed GTX1080 but Monitors stays black

[elMuro]

Hi All

I just installed a Gigabyte GTX1080 G1 Gaming into my PC.
But when I start my PC I do not get anything on my monitor.
My Monitor is a Samsung LU24E590DS.

Before I switched my Graphics Card I had a Geforce 750Ti connceted.
I used the HDMI 1 Slot on my Monitor and the DVI-I slot on my Ge 750 Ti via an adapter because I didnt get a Signal HDMI to HDMI.

Now if I use HDMI to HDMI or Displayport to Displayport, I get no Image.
Strange is, before I switched my Cards I had a Resolution of 3840 x 2160.
But if I enter the Menu in my Monitor it shows DisplayPort 640x480.

I can hear my Win7 starting correctly.

My Motherboard is M5A78L-M with a AMD FX-8350 Processor.
And I got a 600W Power Supply and I connected the 8Pin Power to the card.

Could it be because my Motherboard only has a PCIE 2 and not PCIE 3?

I put my 750Ti inside to install the drivers for the 1080, but still only black screen.

Please Help

 

[AddRAM]

Have you contacted Gigabyte yet ?

 

[elMuro]

Have you contacted Gigabyte yet ?

Yes, they asked me if there is sufficient power.
(I assume there is, 125W for Processor and 180W for G-Card. Recommended by Gigabyte is 500W PSU, I got a 600W PSU)
And they also asked me to test my Card in another system.
(Which I will do maybe today if i am lucky)

I also made following tests:

I used a HDMI cable to connect my PS4, Ge750ti, GTX1080 and my Mobo to my monitor and my TV.

PS4 to TV works
PS4 to Monitor works

750 to TV not working
750 to TV with a DVI Adapter works
750 to Monitor not working
750 to Monitor with a DVI Adapter works

1080 to TV not working
1080 to TV with a DVI Adapter not working
1080 to Monitor not working
1080 to Monitor with a DVI Adapter not working

Mobo to TV not working
Mobo to TV with a DVI Adapter not working
Mobo to Monitor not working
Mobo to Monitor with a DVI Adapter not working

So, my PS4 works fine.
But out of PC i get only a signal by using the Ge750Ti with a HDMI Cable and a DVI Adapter.
Otherwise nothing works.

Could it be that my Mobo is defect?

 

[elMuro]

I replaced my Mobo with a ASRock 970 Extreme3.
But still black screen, neither Graphic Card work now.

 

[elMuro]

I gave my GTX1080 back and got another one, now it works